1. Technical Field
The present invention relates to air conditioning systems and methods, and more particularly, but not by way of limitation, to temperature control assemblies and methods for selective temperature control of enclosures, such as a passenger compartment of a vehicle.
2. History of Related Art
Temperature control systems such as vehicle heaters and air conditioners have improved in recent years. Most common in the transportation industry today are compressor based air-conditioning units that use power from the engine to drive the compressor. When the engine is idling, running the A/C unit may require the engine to idle at higher RPM's. Idling the engine at higher RPM's, however, causes an increase in noise, fuel consumption, and pollution. Furthermore, high fuel prices make it desirable to turn the vehicle's engine off when the vehicle is parked for extended periods of time. In order to run a compressor-based A/C unit while the engine is off, power from the vehicle's battery power is generally needed. Such battery use can, however, only be continued for a short period of time before the battery is completely emptied.
Federal and local regulations have exacerbated the problems associated with the above-mentioned issues. For environmental reasons, vehicles parked at truck stops are often only allowed to idle for a limited period of time, sometimes as little as only a few minutes. These limitations create problems because, for various reasons, vehicle drivers are often required to stay overnight at truck stops. For example, a driver may have reached the maximum number of operating hours allowed by company policy or other regulation, or the driver may have become too tired to continue driving safely.
It is well known that many commercial drivers choose to sleep in their respective vehicles while parked at truck stops or other rest areas. Whether during the day or night, the temperature outside may be too hot to comfortably sleep without air conditioning. In those situations, it would be desirable to have a vehicle air-conditioning unit capable of cooling an interior of the vehicle without running the vehicle's engine. It is also critical that any power consumption will not drain the vehicle's battery below the minimum level required to start the vehicle the next day.
Additionally, the temperature outside the vehicle may be too low for the driver to sleep comfortably in the vehicle without having a heater running. In those situations, it would be desirable to have a heating unit capable of heating an interior of the vehicle without requiring the vehicle's engine to be running. It would also be desirable for the heating unit to heat the interior of the vehicle in such a way that the vehicle's battery is not drained below the minimum level required to start the vehicle.